First Name | Jim |
---|---|
Last Name | Meyer |
Email Address | jmeyer@aviation-repair.com |
Affiliation | |
Subject | Fugitive Emissions Cancer Risk Estimate |
Comment | A key accusation made by CARB against the metal finishing industry is that fugitive emissions may be equally or even more dangerous to the public than stack emissions. I have previously commented on the fiction that cancer risk from stack emissions equals 213 in a million from large chrome plating facilities. Now, it is time to examine the fiction that fugitive emission cancer risks can range to 1,000 chances in a million. The section quoted below is taken directly from Pages F-49 and F-50 of CARB's posted materials. BEGINNING OF QUOTE "Based on the assumptions and model setup described above, staff estimated potential cancer risks ranging from one chance per million to greater than 1,000 chances per million. 4. Conclusion Staff recognizes that this is a high-level directional analysis and is not intended to definitively estimate fugitive emissions rates from specific chrome plating facilities. Nevertheless, the assumptions made are reasonable and this analysis provides information regarding what the potential cancer risks from fugitive emissions might be. Based on these results, it is reasonable to conclude that fugitive emissions of hexavalent chromium from chrome plating facilities are likely to contribute to cancer risks in communities surrounding such facilities." END OF QUOTE The quote specifically states that "The assumptions made are reasonable". You can be the judge. The entire model is described on pages F-45 to F-51. As you can see in the first sentence, CARB is describing the cancer risk model and the data they used to generate their estimate. It is a complex model, and they describe it over several pages. As with all models, it is sensitive to the assumptions made and it is particularly sensitive to the initial data inputs. In this case, CARB does not distinguish themselves. They first attempt to answer the question "how much hex chrome is emitted from an uncontrolled tank?" Surprisingly, CARB does not quote any electrochemical science to answer this question. There is no reference to any science that shows what amount of hex chrome would be dispersed during a plating operation. Are we to believe that in 100 years of chrome plating, no scientist or chemical engineer has ever documented (or computed) the amount of hex chrome mist that comes from uncontrolled tanks? Are we also to believe CARB and/or AQMD in over 30 years of regulating chrome plating tanks have never done any math to compute hex chrome emissions from uncontrolled tanks? CARB should answer these questions because without answers a reasonable person could conclude that established scientific facts did not support CARB's pre-ordained conclusions and had to be dismissed. So, in the absence of science fact, here is the method they used to deduce that uncontrolled tanks produce 1 mg per amp hour of hex chrome emissions. They assumed that emissions are a function of two variables: 1) The arbitrary rule limit for fume suppressant-controlled tanks, and 2) The top-end of the manufacturers stated control efficiency of fume suppressants. Both variables happen to equal 0.1. So, dividing one into the other CARB assesses that the physical chemical electroplating process produces 1 mg per amp hour (0.1 / 0.1 = 1.0). There it is, feed it into the cancer risk model. Some of you are getting the drift here. You can already see that if there was any actual emission science behind the suppressant rule limit of 0.1, CARB could (or would, or should) have used it. You might also question how they decided to use 99% efficiency as their fume suppressant value when they could have used 95%. The answer to that is simple, the 99% assumption drives a higher risk value and supports the desired answer to this "study". But wait, perhaps I am too hasty in attributing to malice that which can be explained in other ways, it is possible that a summer intern performed this analysis and that perhaps the deficiency is a simple lack of quality assurance, audit function, and management oversight. I can't say. Since I believe there are certain science facts relating to physical processes in nature, I don't buy into using the equation on page F-46 (and shown below) as the basis for the starting point to estimate fugitives. Neither should you. "Uncontrolled tank emissions = 0.01 (mg / amp hr) / (1-0.99)" = 1 mg per amp hr But let's give the intern the benefit of the doubt because maybe he only had a couple of hours to produce some data to back up the conclusions about fugitives that he was told to create. QUESTION FOR CARB - WHAT IS THE HEX CHROME EMISSION RATE FROM UNCONTROLLED TANKS? You have been regulating these tanks for decades. Please cite scientific papers or AQMD studies to answer. Wait, there is another troubling aspect to this. Because once we calculate uncontrolled tank emissions, we must figure out what percent of the emissions get past the control systems. CARB was able to locate a US EPA manual about hoods from 1986. They wiped the dust from it, sneezed a couple of times, and ignored the fact that it pre-dated even their first chrome ATCM back in 1988. Now, 36 years later, they chose to construct an estimate of hood capture efficiency by examining it. The book said capture efficiency ranged from 50% to 100%. Yes, that is a wide range. Yes, that range includes 100% - even in 1986. But the intern, or whoever wrote this section, or whoever reviewed the work, makes the following statement. QUOTING "The plating industry uses a different style of hood, but lacking better information about its performance, staff chose to evaluate fugitive emissions using a range of capture efficiency from 85 percent to 95 percent." END QUOTE Are you kidding me? Is CARB so unaware that the source tests that the air districts require, and that we pay $20,000 to execute, have rules about hood capture efficiency? Really? Is CARB aware that this very proposed rule I am commenting on, requires 100% hood capture efficiency by virtue of CARB finally adopting AQMD Rule 1469? Hey CARB, this is how it works. The air districts review and approve our test protocols prior to the test. Then they monitor the test while it is performed. During the test, they observe the slot velocities, and we record them. We must perform video taped smoke tests as confirmation that they capture 100%. Only then, once 100% capture is assured, the HEPA source test is conducted. Following that, for the next few years until the next source test is performed, we are required to maintain the minimum slot velocities and perform ongoing video taped smoke tests to assure that we are always achieving a 100% capture rate. We must keep ongoing records of all this. Inspectors come and review our records and the smoke test videos. The 1,000 chances in a million-cancer risk assertion from fugitive emissions is garbage. It is garbage because the two input variables to your cancer risk model are shown to be garbage. Here is my question for CARB - Is this a case of simple ignorance by CARB? Maybe combined with a lack of management oversight, poor quality assurance, maybe no audit function? Or is it malicious? I know it will be tempting for you to simply declare that this comment is out-of-bounds. That it is not relevant to the fact that you simply changed the decimal point on your computed average of a few source tests. But here is the situation. We are talking about truth and the lack of truth and where CARB stands with respect to the truth about emissions. CARB wants to portray itself as the premier air pollution regulator in the world. To be the leader you must have credibility. To have credibility, you must embrace truth. At this point, it is obvious, South Coast AQMD is the world's premier air regulator. If you do not embrace the truth, you will lose credibility in your other work, which, as I understand it, involves saving the world. Please note also, that on April 14, 2023, two weeks prior to CARB release of the corrected source test numbers on April 27, I alerted Steven Cliff, PhD and Edie Chang to this issue in advance with a heads-up as follows: BEGIN QUOTE "SC AQMD Rule 1469 requires ongoing smoke test validation and periodic monitoring of slot velocities to assure the push/pulls are capturing 100%. We validate this in our source tests. Despite that, the CARB estimate is somewhere between 85% and 95% according to your text and the footnoted source is a tech manual from 1986. The assumption and math that was used to get to the 1 mg / amp hour tank rate is suspect since the rule limit used to start that equation is arbitrary to start with." END QUOTE By all appearances, CARB has chosen not to correct the record regarding the critical element of fugitive emissions. |
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Date and Time Comment Was Submitted | 2023-04-29 18:55:29 |
If you have any questions or comments please contact Clerk of the Board at (916) 322-5594.